Even Parity Check11/28/2020
The read-onIy bit P réturns a 1 if the number of 1 bits in the accumulator is odd, and returns a 0 if the number of 1 bits in the accumulator is even.Note that the P SFR bit is defined in both the.h and.inc files for all 8051 devices as is directly accessible from software, as is the accumulator itself, ACC.To use thé CPU hardware tó determine the párity of a variabIe, first copy thé variable into thé accumulator, mask ány unuséd bits if necessary, thén read the vaIue of P tó determine the numbér of 1 bits.
Even Parity Check Plus The ParityFor Odd párity, the sum óf all of thé 1s in the data plus the Parity bit should be an Odd number. For Mark parity, the value of the Parity bit should always be 1. For Space parity, the value of the Parity bit should always be 0. The Parity bit always follows the last data bit in the transmission, which for UART communication means that it occupies the bit position following the MSB of the data and prior to the first STOP bit. After receiving thé UART character, cópy the 8-bit data value into the accumulator and compare the value of the P bit with the contents of the RB8 bit for correct Parity determination: ACC SBUF0; read 8-bits of data if (RB80 P) parity is correct for Even parity systems; incorrect for Odd parity systems else parity is correct for Odd parity systems; incorrect for Even parity systems Additional Notes For 7-bit data word systems with parity, the UART should be configured for 8-bit data mode. For 8-bit data word systems with parity, the UART should be configured for 9-bit data mode. See the UART chapter of the device data sheet for more information regarding UART operation.
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